A proposed mechanism for diurnal/nocturnal bruxism: hypersensitivity of presynaptic dopamine receptors in the frontal lobe.

There are many reports in the literature concerning nocturnal bruxism, however, diurnal (non-sleep)/nocturnal bruxism is rarely mentioned. We report three patients with diurnal/nocturnal bruxism. They differed from the usual features of nocturnal bruxism in hypoperfusion of the left frontal lobe, a poor response to l-dopa or bromocriptine therapy and a favourable response to metoclopramide. Hypersensitive presynaptic dopamine receptors may be the underlying pathology responsible for this type of bruxism. Regional differences in dopamine receptor pharmacology may explain the perplexing relationship of bruxism to both hyper- and hypo-dopaminergic states.